regarding privilege levels of pentium 4

Sven Eschenberg eschenb@cs.uni-frankfurt.de
Sat Sep 30 20:32:00 GMT 2006


Hi Ranjith,

I might be wrong on this, but I think the question is, if the Operating 
System permits it or under which circumstances. It's neither a question 
of what gcc or the hardware does, but what the OS you are using allows 
to which processes.
It might be, you need 'just' root priviledges, but I'd rather assume, 
that you need to be within the kernel's context, since a cli command 
endangers system stability (it could lead to a lock up) ...

Regards

-Sven

ranjith kumar wrote:
>  Hi,
>
>
>   How can we tell at what privilege level a program is
> running.
>   Is it possible to run a program at privilege level
> 'zero' on a processor
> like Pentium 4.
>
>    Actually I want to disable interrupts while running
> my program. This
> can be done by "cli" instruction. Using "asm inline"
> feature of GCC, we
> can include assembly instructions  in programs of C,
> C++...etc.
>
>     But the problem is that "cli" instruction can be
> executed only at
> privilege level "zero".
>
> Can anyone  help me.
>
>
>
>
> Thanking you.
>
>
> 	
> 	
> 		
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